1. Field of the Invention
The present invention is generally drawn a method of testing the integrity of boiler tubes and more particularly for localized testing of same with a unique test probe.
2. Description of the Prior Art
Testing boiler tubes for defects is known in the art and various methods and apparatus are employed.
Eddy current meters are passed through tubing and defects such as cracks in the tubing and thin wall sections are detected thereby. U.S. Pat. No. 5,025,215 teaches the use of such eddy current meters to detect defects in steam boiler tubes.
It is also known to plug steam tubing with a plug having grasping fingers and urethane seals and then to subject it to a high pressure to determine if there is any leakage therefrom. Such a method and plug are disclosed in U.S. Pat. No. 4,385,643.
However, toate there was no teaching in the prior art of localizing a particular area of the steam tubing which may have a potential tube problem and then sealing only this localized section and subjecting it to pressures in excess of normal operating pressures to determine if this defect is one that will fail in service.
The present invention solves the problems associated with prior art devices and others by providing a unique steam tube testing method and apparatus for same whereby tubes are checked for potentially defective areas which may fail in the future by leaking and to a special probe used for isolating and high pressure testing these areas.
The method involves first testing the boiler tube for defective areas using an electromagnetic probe. Once the defective area is thus identified and localized, a probe is inserted about 3xe2x80x3 past the defect using a probe applicator. The probe is then sealed to the inside of the tube and the applicator is removed. A second probe is similarly located on the other side of the defect. The tube section between the two probes is then filled with water to evacuate all air there from that may cause a bad reading and the tube is fluid pressurized to approximately 3xc3x97 the normal steam tubing operating pressure to see if the defect is truly a defect which may result in a leak. If a leakage results, the tube is later sealed in a known manner. If there is no leak, the tube is deemed operationally fit. The probes are then removed and another area is similarly checked.
The probe assembly comprises the probe and the applicator for driving the probe to the desired location. The probe uses a stack of Belleville style washers that are compressed to relax a series of locking fingers allowing the probe to be moved to the location by the applicator. Once there, the washers are expanded to lock the fingers to the tube and to expand urethane seals to seal the tube. The applicator is then removed and a water supply probe is inserted in the tube creating the localized chamber.
In view of the foregoing it will be seen that one aspect of the present invention is to provide a method and apparatus for checking a localized section of steam tubing for potential future failure.
Another aspect is to provide an easily inserted and retracted apparatus for sealing a section of steam tubing.
Yet another aspect is to provide a method and apparatus for testing the integrity of steam tubing exclusively from the inside of the tubing allowing for simultaneous testing of the tubing outside surface.
These and other aspects of the present invention will be more fully understood upon a review of the following description of the preferred embodiment when considered in conjunction with the drawings.